Thoracic Wall Coverings •Skin– Thin anteriorly & thick posteriorly, variable hair distribution • Superficial Fascia – More dense posteriorly • Deep Fascia – Thin , ill defined for free movement of chest for breathing • Extrinsic muscles –Upper limb , Back, Abdomen & Head & Neck Supraclavicular nerves ------ -·--------T2 - - --------·----3 - - ....- (i;:· - - - - --~ -- -- :' -,- .... :---- ; 5 -- - -- -------- -- - ---------6 -- - -----7 --- 8 Lateral - --- --- cutaneous --- -.. _ 9 ~ branches of --- --- thoracic nerves 10 Go'.)~ ------- Lateral cutaneous ........ ... .... _ .... _ branches of twelfth Lateral femoral cutaneous nerve t---- - -++- Femoral branch of genitofemoral nerve Intercostal Spaces • Eleven (11) intercostal spaces on each side • Last two spaces are open in front Features of Space • Each directed downward & forward • Narrow towards vertebral column & broad towards sternum, widest at costo-chondral junction • Posterior part is inter-osseous while ant part is inter- cartilaginous Contents – Intercostal muscles , vessels & nerves Intercostal Spaces Typical I/C space Spaces b/w typical ribs & transversed by nerves & vessels & confined to thoracic wall Boundaries of a typical I/c space – 3rd to 6th • Above – Sharp lower margin of upper rib & its cartilage •Below– Blunt upper margin of lower rib & its cartilage • In front – Lateral border of sternum b/w costal notches •Behind– Body of corresponding thoracic vertebra Intercostal muscles Arranged in three sheets from outside inward • External Intercostal • Internal Intercostal • Transverses thoracis – intercostalis intimi Subcostalis sternocostalis Main action Prevent retraction during inspiration & bulging during expiration of the intercostal spaces lntercostal vessels lntercosta/ nerve Innermost intercosta/ Internal intercostal External intercostal External Intercostal Origin:Lower border of the rib above. OuterInsertion: lip of upper border of rib below. Extent:From costocondral anteriorly to tubercle of junctionrib posteriorly. lntercosta l Medial to costochondral junction vessels lntercostal replaced by external (Ant.) intercostal nerve Innermost membrane. interrosla/ - , .,,,.• Direction of fibres: Downwards and laterally at the back and External intercostaJ Downwards, forwards and medially in front. INTERNAL INTERCOSTAL MUSCLE Origin: Floor of costal groove of rib above. Insertion: Superior border of rib below (inner to the attachment of external intercostal muscle). lntercosta l Extent: ~ssels From lateral border of sternum lntercostaf nerve anteriorly to angle of rib posteriorly. Innermost intercosfal Medial to it, replaced by internal(Posterior) intercostal membrane. fntema, Direction of fibres: intercostal External intercostaf At right angle to the direction of external intercostal. INNERMOST INTERCOSTAL (Intercostalis Intimi) Origin: Upper margin of subcostal groove of rib above. vessels lntercostal Insertion: nerve Innermost inten;ostal Superior border of rib below (inner to the attachment of internal intercostal muscle), Extent: External intercostal Present in middle two fourths of the lower intercostal spaces. Poorly developed or even absent in the upper spaces. Direction of fibres: Same as internal intercostal (at right angle to the direction of external intercostal). Sternocostalis or TI1 ora cic \~l all Internal \ 7 Present on the inner surface of anterior thoracic wall. Origin: Lower 1/3 of posterior surface of body of sternum, Posterior surface of xiphoid & posterior surfaces of costal cartilages of 4th to 7th ribs. Insertion: Lower border and posterior surfaces costal cartilages of 2nd to 6th ribs. Attachments are variable and may even differ on the two sides. Direction of fibres:Lowest fibres are horizontal, become gradually oblique and upper most fibres are directed upwards and laterally. Subcostalis Present on the inner aspect of intercostal spaces posteriorly. Origin:Inner surface of rib above, near its angle. Insertion: Inner surface of second or ~L Tra third rib below. ~ r--:=:::.:~ t/Jo Extent: Confined to post. Part of the lower spaces only Direction of fibres: Same as innermost intercostal. , Anterior Vi "' ·- Ribs: Serratus posterlor- -n:::v-~ r­ superior Levator ~~j;,c=:::::::::::....~ ~ ,....Tr:ansversus costarum Innermost lfloracis intercostal Serratus posterior--;-,,..______,.;;:;:;:;:~ inferior Posterior View Anterior View lntercoslal~em:;{ _ .;.:,.._.,. External interoostal membrane Body of ste rnum Internal interoosllll Internal intercostal Lateral View Actions • Ext. intercostal-Inspiration, moves ribs superiorly • Int. intercostal- Expiration, moves ribs inferiorly • Innermost intercostal-Expiration • Subcostales – depress ribs • S.P.S elevates sup. 4 ribs, raising the sternum and AP diameter • S.P.I. depresses the inf. Ribs, so prevents then to be picked sup. By dia. • Transverse throcis • Lev. Costarum unimportant Intercostal vessels • Each space has arteries arranged in two groups – Anterior(2) & posterior (1) • Veins also correspond to arteries & are arranged in two groups – Anterior(2) & posterior(1) • Intercostal nerves are 11 in no. on each side & are the ventral ramus of thoracic nerve Intercostal Arteries Post intercostal artery • 11 on each side • One in each space • 1,2 – from superior IC artery (branch of costo-cervical trunk of subclavian • 3 – 11 – from descending thoracic aorta (Aortic intercostal arteries of Rt. Side are longer) TI1oracic Section Anterior ramus Transverse process ] of thoracic nerve Superior costotransverse ligament Radiate ligament of head of rib Su bcostal1----,-,= Anterior longitudinal ligament sels and nerve inches of intercostal vessels and nerve Communicating branches / (rami communicantes) ~ Splanchnic nerve Anterior View Sympathetic trunk Post. Intercostal artery Course Rt. Post IC artery arise from back of aorta Pass backward & laterally in front of Vertebral column & behind oesophagus , thoracic duct & azygos vein & sympathetic trunk Left passes behind Hemiazygos vein & sympathetic trunk In the Space Accompanied by vein & nerve VAN – from above down wards Post. Intercostal artery • Each artery passes upward & laterally toward angle of upper rib • Run along the costal groove between 2nd & 3rd layer • Give a collateral branch at angle of rib &main branch continue & anastomose with upper anterior intercostal artery & collateral with lower ant. IC artery at costochondral junction Anterior Intercostal artery • Present in all spaces except last two which are open in front 1-6 arise from internal thoracic artery 7-9 from musculophrenic artery Each space has two (upper & lower) Venous drainage • Ant.IC Veins (upper 6 space) – internal thoracic V • Rest in musculophrenic vein • Post. IC Vein – one in each space Ist IC space – On Rt. & Lt.brachiocephalic vein 2nd , 3rd & 4th IC space –Form Rt. superior IC vein which drain in Azygos vein On left side form Lt superioor IC vein which drain in Lt brachiocephalic V 5th to 11th (Right) azygos vein 5th to 8th (Left) acc. Hemiazygos 9th to 11th (Left) hemiazygos 12th – subcostal vein Typical TI1oracic SpiI1al Ne1,.,.re Lateral branch "' Superior costotransverse ligament Medial branch Posterior intercostal membrane Subcostalis Dorsal ramus Rami communicantes Sympathetic ganglion ~...,,,..t-t-- lntercostal nerve (ventral ramus) cutaneous branch Innermost Pleura intercostal Transversus thoracis Internal thoracic artery External intercostal Anterior cutaneous branch .